class Tins::Unit::UnitParser

def scan_unit
  case
  when scan(@unit_re)
    prefix = @unit_re.prefixes.find { |pre| pre.name == self[1] } or return
    @number *= prefix.multiplier
  when scan(@unit_lc_re)
    prefix = @unit_lc_re.prefixes.find { |pre| pre.name == self[1] } or return
    @number *= prefix.multiplier
  when scan(@unit_uc_re)
    prefix = @unit_uc_re.prefixes.find { |pre| pre.name == self[1] } or return
    @number *= prefix.multiplier
  end
end