Python3 Syntax Symbol Uses

^C

II

control-C

Interrupt execution on Microsoft Windows systems.

^D

II

control-D

Interrupt execution on Unix-derived systems.

\t

P

tab(s) code

Syntactically significant indentation. Do not mix with spaces.

I

token_a whitespace(s) token_b

Whitespace is tab, newline, and space. Optional unless token_atoken_b run together would mean something else.

\n

S

code \n

Physical line, also logical line unless preceded by '\' or inside (), [], or {} pairs.

I

token \n token

Whitespace when preceded by '\' or inside (), [], or {} pairs; see infix \t.

\r

S

code \r\n or \r

Deleted or converted to \n.

P

space(s) code

Syntactically significant indentation. Do not mix with tabs.

I

token token

Whitespace; see infix \t.

!=

I

object1 != object2

Comparison operator for inequality of object values.

" "

PS

" text "

Single-quoted* string or bytes literal, cannot contain a newline (\n) character. *by one double-quote character

PS

""" text """

Triple-quoted* string or bytes literal, possibly spanning multiple lines. *by three double-quote characters

#

P or I

code # any_text

Comment ended by \n and optionally preceded by code.

$

<not used>

%

I

number1 % number2

Remainder (modulo) operator, 2 % 2 == 0, 3 % 2 == 1.

I

format_string % data

%-format format-string using %-format specifications.

P

%format_spec

Format within %-format strings for interpolated value. See Standard-library Built-in-types Sequence-types Old-string-formatting section for more.

%=

I

target %= expression

See op=.

%%

' x %% y '

Insert % rather than formatted value when used within %-format strings.

&

I

intset1 & intset2

Integer bitwise-and or set union operator.

&=

I

target &= expression

See op=.

' '

PS

' text '

Single-quoted string or bytes literal, cannot contain a newline (\n) character.

PS

''' text '''

Triple-quoted string or bytes literal, possibly spanning multiple lines.

( )

()

Empty tuple.

PS

( expression )

Separate expression from surrounding code as a syntactic atom.

PS

( comprehension )

Generator expression, with ( ) optional in one-arg calls.

IS

name ( base_classes )

Header for class definitions.

IS

name ( parameters )

Header for function definitions.

IS

callable ( arguments )

Call operator for functions, classes, and other callables.

*

*

In function parameter list, make following unstarred names keyword only.

P

*parameter_name

Function parameter bound to a tuple of extra positional arguments, any following unstarred names are keyword only.

P

*iterable

In a call, unpack iterable items as arguments.

P

*assignment_target

Starred target in assignment statement gets extra items from iterable.

I

number1 * number2

Number multiplication operator.

I

n * sequence or sequence * n

Operator to concatenate n copies of sequence.

S

from module import *

Import all public (non-private) names from the module.

*=

I

target *= expression

See op=.

**

P

**parameter_name

Function parameter bound to dict of extra keyword arguments.

P

**mapping

In a call, treat the key:value pairs as extra keyword arguments.

I

number1 ** number2

Exponentiation operator, number1 to the power number2.

**=

I

target **= expr

See op=.

+

P

+ number

The same as number, unless a class decides otherwise (rare).

I

number1 + number2

Number addition operator.

I

sequence1 + sequence2

Sequence concatenation operator.

+=

I

target += expression

See op=.

,

I

expression1, expression2

Delimiter for expression list that becomes a tuple unless appearing within [ ], { }, or func( ) to become list, set, dict, or param/arg list.

-

P

-number

Minus operator, negates the number.

I

number1 - number2

Number subtraction operator, number1 minus number2.

I

set1 - set2

Set difference operator, members of set1 not in set2.

-=

I

target -= expression

See op=.

.

P

.module

Used in relative imports but not well documented.

I

integer.fracton

Float literal, with either integer or fraction part (but not both) optional.

I

name.attribute

Dotted name that references attribute of object denoted by name.

I

package.sub_mod

Import a subpackage or module from package in import statement.

...

Ellipsis literal.

/

I

number1 / number2

Number division (quotient) operator, 1/2 == 0.5.

/=

I

target /= expression

See op=.

//

I

number1 // number2

Floor division operator, 1/2 == 0.

//=

I

target //= expression

See op=.

:

I

int1 : int2 : int3

Start, stop, and step for slicing, with in1, int2, and :int3 optional.

I

key : value

Delimiter for dict display items.

I

lambda arglist : expression

Lambda expression, abbreviates function definition.

I

param : expression

In parameter lists, add entry to function.__annotations__.

S

header :

Delimiter for header of compound statements, followed by a statement suite.

;

I

statement ; statement

Delimiter separating multiple statements on one physical line.

<

I

value1 < value2

Comparison operator for value1 less than value2.

<=

I

value1 <= value2

Comparison operator for value1 less than or equal to value2.

<<

I

integer << count

Left shift operator, i << j == i * 2**j.

<<=

I

target <<= expr

See op=.

=

I

param = value

In parameter lists, make the value the default argument for the parameter.

I

target = expression targets = iterable

Delimiter for assignment statements.

op=

I

target op= compatible_object

Delimiter for augmented assignment statements. Op can be infix +, -, *, /, //, %, **, &, |, ^, <<, or >>. Similar to 'target = target op value' except that target is evaluated only once and mutable targets get mutated instead of replaced.

==

I

value1 == value2

Comparison operator for equality of object values.

>

I

value1 > value2

Comparison operator for value1 great than value2.

>=

I

value1 >= value2

Comparison operator for value1 greater than or equal to value2.

>>

I

integer >> count

Right shift operator, i >> j == i // 2**j.

>>=

I

target >>= expr

See op=.

?

<not used>

@

P

@decorator

Wrap or modify the following class or function by calling the decorator.

[ ]

PS

[ display ]

With display an expression list or comprehension, make a new list.

IS

seqmap [ index ]

Subscript a sequence with an integer or slice or subscript a map with a hashable object.

\

P

\char(s)

Escape character changes meaning of following char(s) in string or bytes literals.

P

\newline-char

Outside quotes, allows logical line to continue on next physical line.

^

I

intset1 ^ intset2

Integer bitwise exclusive-or or set symmetric-difference operator.

^=

I

target ^= expression

See op=.

_

An 'honorary' letter when used in identifiers (names).

II

Default name bound to expressions used as statements.

P

_name

Private identifier, meaning is conventional except in * imports.

__

P

__name

Private identifier that gets mangled.

__ __

PS

__name__

Special, reserved name used by Python interpreters.

`

<not used>

{ }

PS

{ display }

With display an expression list or comprehension, make a new set, unless the display items are key:value pairs, in which case make a new dict, or unless there is no display, in which case make a new empty dict.

IS

{ format-spec }

Format within str.format() string for interpolated value. See Standard-library String-services string Format String section for more.

{{,}}

'x {{ y }} z'

Insert { or } rather than formatted value when used within str.format strings.

|

I

intset1 | intset2

Integer bitwise inclusive-or or set union operator.

|=

I

target |= expression

See op=.

~

P

~integer

Bitwise inversion operator, ~n == -(n+1).