get-buffer

get-buffer is a built-in function in `C source code'.

(get-buffer BUFFER-OR-NAME)

Return the buffer named BUFFER-OR-NAME.
BUFFER-OR-NAME must be either a string or a buffer. If BUFFER-OR-NAME
is a string and there is no buffer with that name, return nil. If
BUFFER-OR-NAME is a buffer, return it as given.