'Determine whether a given term is in a formula.'

def hasterm(self, query_term):

    if (not isinstance(query_term, Formula)):
        if isinstance(query_term, string_types):
            try:
                query = self[query_term]
                return (query.termname in self.termnames())
            except:
                return False
        elif isinstance(query_term, Term):
            return (query_term.termname in self.termnames())
    elif (len(query_term.terms) == 1):
        query_term = query_term.terms[0]
        return (query_term.termname in self.termnames())
    else:
        raise ValueError('more    than    one    term    passed    to    hasterm')
