flow like the river

VISUALIZACION/node_modules/graphql/validation/rules/UniqueVariableNamesRule.js

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+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.UniqueVariableNamesRule = UniqueVariableNamesRule;
+
+var _GraphQLError = require("../../error/GraphQLError.js");
+
+/**
+ * Unique variable names
+ *
+ * A GraphQL operation is only valid if all its variables are uniquely named.
+ */
+function UniqueVariableNamesRule(context) {
+  var knownVariableNames = Object.create(null);
+  return {
+    OperationDefinition: function OperationDefinition() {
+      knownVariableNames = Object.create(null);
+    },
+    VariableDefinition: function VariableDefinition(node) {
+      var variableName = node.variable.name.value;
+
+      if (knownVariableNames[variableName]) {
+        context.reportError(new _GraphQLError.GraphQLError("There can be only one variable named \"$".concat(variableName, "\"."), [knownVariableNames[variableName], node.variable.name]));
+      } else {
+        knownVariableNames[variableName] = node.variable.name;
+      }
+    }
+  };
+}