write text table of depth-01 GO terms and their letter representation.

def prt_header(prt, title=None, pre=''):
        """write text table of depth-01 GO terms and their letter representation."""
        if title is not None:
            prt.write("{PRE}{TITLE}\n".format(TITLE=title, PRE=pre))
            prt.write('{PRE}\n'.format(PRE=pre))
        prt.write("{PRE}    D1 : Letter representing the depth-01 GO term\n".format(PRE=pre))
        prt.write("{PRE}    dcnt: Total number of all descendants\n".format(PRE=pre))
        prt.write("{PRE}    dep: Depth; The maximum length path to ".format(PRE=pre))
        prt.write("{PRE}leaf-level (childless) GO descendant(s)\n".format(PRE=pre))
        prt.write("{PRE}\n".format(PRE=pre))
        prt.write("{PRE}D1 NS  dcnt dep GO ID      Description\n".format(PRE=pre))
        prt.write("{PRE}- -- ------ --- ---------- ------------------------------\n".format(
            PRE=pre))