code: function getNonNumericOperand(node) {
      const left = node.left,
          right = node.right;
  
      if (right.type !== "BinaryExpression" && !isNumeric(right)) {
          return right;
      }
  
      if (left.type !== "BinaryExpression" && !isNumeric(left)) {
          return left;
      }
  
      return null;
  }
docs: Returns the first non-numeric operand in a BinaryExpression. Designed to be
  used from bottom to up since it walks up the BinaryExpression trees using
  node.parent to find the result.
  @param {BinaryExpression} node The BinaryExpression node to be walked up on
  @returns {ASTNode|null} The first non-numeric item in the BinaryExpression tree or null