'Extract the type and contents of this field from the file.
Returns tuple (<type>, <field-value>) or None if field does not exist.'

def get_type_and_value(self, field_name):

    fields = self.list_fields_and_values([field_name])
    if (not fields):
        return None
    (field_name, value_type, value) = fields[0]
    return (value_type, value)
