Read a character from the command input (keyboard or macro).
It is returned as a number. Non-character events are ignored.
If the character has modifiers, they are resolved and reflected to the
character code if possible (e.g. C-SPC -> 0).
If the optional argument PROMPT is non-nil, display that as a prompt.
If the optional argument INHERIT-INPUT-METHOD is non-nil and some
input method is turned on in the current buffer, that input method
is used for reading a character.
If the optional argument SECONDS is non-nil, it should be a number
specifying the maximum number of seconds to wait for input. If no
input arrives in that time, return nil. SECONDS may be a
(fn &optional PROMPT INHERIT-INPUT-METHOD SECONDS)