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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def source_headers(self):
 """"Returns the headers for the resource source. Specifically, does not include any header that is the EMPTY_SOURCE_HEADER value of _NONE_"""


        t = self.schema_term

        if t:
            return [self._name_for_col_term(c, i)
                    for i, c in enumerate(t.children, 1) if c.term_is("Table.Column")
                    and c.get_value('name') != EMPTY_SOURCE_HEADER
                    ]
        else:
            return None