'write_into(output_file [, eol])
Serialize current state into `output_file`.
`output_file` -> Any instance that respond to `write()`, typically a
file object'

def write_into(self, output_file, eol=None):

    output_eol = (eol or self.eol)
    for item in self:
        string_repr = str(item)
        if (output_eol != '\n'):
            string_repr = string_repr.replace('\n', output_eol)
        output_file.write(string_repr)
        if (not string_repr.endswith((2 * output_eol))):
            output_file.write(output_eol)
