code: function addTracingToResolvers(schema) {
    // XXX this is a hacky way of making sure that the schema only gets decorated
    // with tracer once.
    if (schema._apolloTracerApplied) {
      // console.log('Tracing already added to resolve functions. Not adding again.');
      return;
    }
    // eslint-disable-next-line no-param-reassign
    schema._apolloTracerApplied = true;
  
    forEachField(schema, (field, typeName, fieldName) => {
      const functionName = `${typeName}.${fieldName}`;
      if (field.resolve) {
        // eslint-disable-next-line no-param-reassign
        field.resolve = decorateWithTracer(
          field.resolve,
          { type: 'resolve', functionName },
        );
      }
    });
  }
docs: This function modifies the schema in place to add tracing around all resolve functions