Insert text into the current buffer, with faces.
Arguments from ARGS should be either strings; functions called
with no args that return a string; pairs `:face FACE', where FACE
is a face specification usable with `put-text-property'; or pairs
`:link LINK' where LINK is a list of arguments to pass to
`insert-button', of the form (LABEL ACTION [HELP-ECHO]), which
specifies the button's label, `action' property and help-echo string.
FACE and LINK can also be functions, which are evaluated to obtain
a face or button specification. (fn &rest ARGS)