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.