<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def parse_host(self, tup_tree):
 """ Parse a HOST element and return its text content as a unicode string. :: <!ELEMENT HOST (#PCDATA)> """


        self.check_node(tup_tree, 'HOST', (), (), (), allow_pcdata=True)

        return self.pcdata(tup_tree)