Expression statements are used (mostly interactively) to compute and
write a value, or (usually) to call a procedure (a function that
returns no meaningful result; in Python, procedures return the value
None):
expression_stmt: condition_list
An expression statement evaluates the condition list (which may be a single condition).
In interactive mode, if the value is not None, it is converted
to a string using the rules for string conversions (expressions in
reverse quotes), and the resulting string is written to standard
output (see section 
) on a line by itself.
(The exception for None is made so that procedure calls, which
are syntactically equivalent to expressions, do not cause any output.)