<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def split_spec(spec, sep):
 """Split a spec by separator and return stripped start and end parts."""

    parts = spec.rsplit(sep, 1)
    spec_start = parts[0].strip()
    spec_end = ''
    if len(parts) == 2:
        spec_end = parts[-1].strip()
    return spec_start, spec_end