<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def write_to_file(directory=None, callback=None, overwrite=True):
    '''Create a callback handler for asynchronous Body handling.

    If provided, the callback will be invoked as described in
    :py:meth:`planet.api.models.Body.write`. In addition, if the download
    is skipped because the destination exists, the callback will be invoked
    with ``callback(skip=body)``.

    The name of the file written to will be determined from the Body.name
    property.

    :param directory str: The optional directory to write to.
    :param callback func: An optional callback to receive notification of
                          write progress.
    :param overwrite bool: Overwrite any existing files. Defaults to True.
    '''

    def writer(body):
        file = os.path.join(directory or '.', body.name)
        if overwrite or not os.path.exists(file):
            body.write(file, callback)
        else:
            if callback:
                callback(skip=body)
            body.response.close()
    return writer