Vim has its own built-in Python interpreter. Thus it could use a different version of the default interpreter for the operating system.

To check with which version of Python Vim was compiled, type the following command:

:python import sys; print(sys.version)

This imports the sys module and prints its version property, containing the version of the currently used Python interpreter.

To be able to use vim commands in Python, the vim module should be imported.

:python import vim

After having this module imported, the user has access to the command function:

:python vim.command("normal iText to insert")

This command would execute i in normal mode then type Text to insert and fall back to normal mode.

Every Python statement in Vim should be prefixed with the :python command, to instruct Vim that the next command is not Vimscript but Python.

To avoid typing this command on each line, when executing multi-line Python code, it is possible to instruct Vim to interpret the code between two marker expressions as Python.

To achieve this, use:

:python << {marker_name}
a = "Hello World"
print(a)
{marker_name}

where {marker_name} is the word you want to use to designate the end of the python block.

E.g.:

:python << endpython
surname = "Doe"
forename = "Jane"
print("Hello, %s %s" % (forename, surname))
endpython

would print:

Hello, Jane Doe