# Expressions

COMMENT: **This page is being refactored**

This chapter explains the meaning of the elements of expressions in Python.

## Atoms

Atoms are the most basic elements of expressions. The simplest atoms
are **identifiers** or **literals**. Subexpressions enclosed in reverse
quotes or in parentheses, brackets or braces are also categorized
syntactically as atoms.

An atom can be one of:

- Identifiers
- Literals
**parenthesized-forms****list-displays****generator-expressions****dictionary-displays****string-conversions**- Primaries:
**syntax-primary**

See **syntax-atom**.

## Arithmetic conversions

When a description of an arithmetic operator below uses a phrase
like the numeric arguments are converted to a common type,

the arguments are coerced using Python’s standard **coercion-rules**.
If both arguments are standard numeric types, the following coercions
are applied:

- If either argument is a complex number, the other is converted to complex;
- otherwise, if either argument is a floating point number, the other is converted to floating point;
- otherwise, if either argument is a long integer, the other is converted to long integer;
- otherwise, both must be plain integers and no conversion is necessary.

Some additional rules apply for certain operators (e.g., a string left argument to the ‘%’ operator). Extensions can define their own coercions.