How to use the @graphql-codegen/visitor-plugin-common.DocumentMode.string function in @graphql-codegen/visitor-plugin-common

constructor(schema: GraphQLSchema, fragments: LoadedFragment[], rawConfig: RawClientSideBasePluginConfig) {
    super(schema, fragments, rawConfig, {});

    autoBind(this);

    this._additionalImports.push(`import { GraphQLClient } from 'graphql-request';`);

    if (this.config.documentMode !== DocumentMode.string) {
      this._additionalImports.push(`import { print } from 'graphql';`);
    }
  }

.map(o => {
        const optionalVariables = !o.node.variableDefinitions || o.node.variableDefinitions.length === 0 || o.node.variableDefinitions.every(v => v.type.kind !== Kind.NON_NULL_TYPE || v.defaultValue);
        const doc = this.config.documentMode === DocumentMode.string ? o.documentVariableName : `print(${o.documentVariableName})`;
        return `${o.node.name.value}(variables${optionalVariables ? '?' : ''}: ${o.operationVariablesTypes}): Promise<${o.operationResultType}> {
  return client.request<${o.operationResultType}>(${doc}, variables);
}`;
      })
      .map(s => indentMultiline(s, 2));