def lhs
      raise ScopedSearch::Exception, "Operator does not have a LHS" if prefix?
      raise ScopedSearch::Exception, "Operators with more than 2 children do not have LHS/RHS" if children.length > 2
      children[0]
    end
def lhs
      raise ScopedSearch::Exception, "Operator does not have a LHS" if prefix?
      raise ScopedSearch::Exception, "Operators with more than 2 children do not have LHS/RHS" if children.length > 2
      children[0]
    end
Return the left-hand side (LHS) operand for this operator.