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**Updated**
. put dependency on pyexcel-io 0.5.0, which uses cStringIO instead of StringIO.
Hence, there will be performance boost in handling files in memory.
**Relocated**
. All ods type conversion code lives in pyexcel_io.service module
. `4 <https://github.com/pyexcel/pyexcel-odsr/issues/4>`_, handle unseekable
stream given by http response.