flow like the river

VISUALIZACION/node_modules/graphql/validation/rules/LoneAnonymousOperationRule.js.flow

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+// @flow strict
+import { GraphQLError } from '../../error/GraphQLError';
+
+import type { ASTVisitor } from '../../language/visitor';
+import { Kind } from '../../language/kinds';
+
+import type { ASTValidationContext } from '../ValidationContext';
+
+/**
+ * Lone anonymous operation
+ *
+ * A GraphQL document is only valid if when it contains an anonymous operation
+ * (the query short-hand) that it contains only that one operation definition.
+ */
+export function LoneAnonymousOperationRule(
+  context: ASTValidationContext,
+): ASTVisitor {
+  let operationCount = 0;
+  return {
+    Document(node) {
+      operationCount = node.definitions.filter(
+        (definition) => definition.kind === Kind.OPERATION_DEFINITION,
+      ).length;
+    },
+    OperationDefinition(node) {
+      if (!node.name && operationCount > 1) {
+        context.reportError(
+          new GraphQLError(
+            'This anonymous operation must be the only defined operation.',
+            node,
+          ),
+        );
+      }
+    },
+  };
+}