<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _fusion_range_to_dsl(tokens) -> FusionRangeBase: """Convert a PyParsing data dictionary into a PyBEL. :type tokens: ParseResult """

    if FUSION_MISSING in tokens:
        return missing_fusion_range()

    return fusion_range(
        reference=tokens[FUSION_REFERENCE],
        start=tokens[FUSION_START],
        stop=tokens[FUSION_STOP]
    )