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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 src_callback_read(state, ratio, frames, data):
 """Read up to `frames` worth of data using the callback API. Returns ------- frames : int Number of frames read or -1 on error. """

    data_ptr = ffi.cast('float*f', ffi.from_buffer(data))
    return _lib.src_callback_read(state, ratio, frames, data_ptr)