These first two commands are also intended primarily for use within
the <code> argument of \DeclareOption or \DeclareOption*.
\AtEndOfClass {<code>}
\AtEndOfPackage {<code>}
These commands declare <code> that is saved away internally and then executed after processing the whole of the current class or package file.
Repeated use of these commands is permitted: the code in the arguments is stored (and later executed) in the order of their declarations.
\AtBeginDocument {<code>}
\AtEndDocument {<code>}
These commands declare <code> to be saved internally and executed
while LaTeX is executing \begin{document} or |