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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 docify(self, df):
 """ Convert a Pandas DataFrame to SON. Parameters df: DataFrame The Pandas DataFrame to encode """

        dtypes = {}
        masks = {}
        lengths = {}
        columns = []
        data = Binary(b'')
        start = 0

        arrays = []
        for c in df:
            try:
                columns.append(str(c))
                arr, mask = self._convert_types(df[c].values)
                dtypes[str(c)] = arr.dtype.str
                if mask is not None:
                    masks[str(c)] = Binary(compress(mask.tostring()))
                arrays.append(arr.tostring())
            except Exception as e:
                typ = infer_dtype(df[c], skipna=False)
                msg = "Column '{}' type is {}".format(str(c), typ)
                logging.info(msg)
                raise e

        arrays = compress_array(arrays)
        for index, c in enumerate(df):
            d = Binary(arrays[index])
            lengths[str(c)] = (start, start + len(d) - 1)
            start += len(d)
            data += d

        doc = SON({DATA: data, METADATA: {}})
        doc[METADATA] = {COLUMNS: columns,
                         MASK: masks,
                         LENGTHS: lengths,
                         DTYPE: dtypes
                         }

        return doc