<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_qseq_dir(fc_dir):
 """Retrieve the qseq directory within Solexa flowcell output. """

    machine_bc = os.path.join(fc_dir, "Data", "Intensities", "BaseCalls")
    if os.path.exists(machine_bc):
        return machine_bc
    # otherwise assume we are in the qseq directory
    # XXX What other cases can we end up with here?
    else:
        return fc_dir