code: function checkForStringConcat(node) {
              if (!astUtils.isStringLiteral(node) || !isConcatenation(node.parent)) {
                  return;
              }
  
              const topBinaryExpr = getTopConcatBinaryExpression(node.parent);
  
              // Checks whether or not this node had been checked already.
              if (done[topBinaryExpr.range[0]]) {
                  return;
              }
              done[topBinaryExpr.range[0]] = true;
  
              if (hasNonStringLiteral(topBinaryExpr)) {
                  context.report({
                      node: topBinaryExpr,
                      message: "Unexpected string concatenation.",
                      fix: fixer => fixNonStringBinaryExpression(fixer, node)
                  });
              }
          }
docs: Reports if a given node is string concatenation with non string literals.
  
  @param {ASTNode} node - A node to check.
  @returns {void}