asymptote: plain
8.1 'plain'
===========
This is the default 'Asymptote' base file, which defines key parts of
the drawing language (such as the 'picture' structure).
By default, an implicit 'private import plain;' occurs before
translating a file and before the first command given in interactive
mode. This also applies when translating files for module definitions
(except when translating 'plain', of course). This means that the types
and functions defined in 'plain' are accessible in almost all
'Asymptote' code. Use the '-noautoplain' command-line option to disable
this feature.