def match_characteristics(other)
      chr = characteristics
      ochr = other.characteristics
      chr and ochr and chr.tissue_side == ochr.tissue_side and chr.tissue_site == ochr.tissue_site
    end
def match_characteristics(other)
      chr = characteristics
      ochr = other.characteristics
      chr and ochr and chr.tissue_side == ochr.tissue_side and chr.tissue_site == ochr.tissue_site
    end
Returns whether this SpecimenRequirement characteristics matches the other SpecimenRequirement characteristics
 on the tissue site and tissue side.