Check for common user command-line errors.

def _chk_docopts(self, kws):
        """Check for common user command-line errors."""
        # outfile should contain .png, .png, etc.
        outfile = kws['outfile']
        if len(kws) == 2 and os.path.basename(kws['obo']) == "go-basic.obo" and \
            kws['outfile'] == self.dflt_outfile:
            self._err("NO GO IDS SPECFIED", err=False)
        if 'obo' in outfile:
            self._err("BAD outfile({O})".format(O=outfile))
        if 'gaf' in kws and 'gene2go' in kws:
            self._err("SPECIFY ANNOTAIONS FROM ONE FILE")
        if 'gene2go' in kws:
            if 'taxid' not in kws:
                self._err("SPECIFIY taxid WHEN READ NCBI'S gene2go FILE")