class_docstr: Load fastMRI files with '.h5' suffix. fastMRI files, when loaded with "h5py",
  are HDF5 dictionary-like datasets. The keys are:
  
  - kspace: contains the fully-sampled kspace
  - reconstruction_rss: contains the root sum of squares of ifft of kspace. This
      is the ground-truth image.
  
  It also has several attributes with the following keys:
  
  - acquisition (str): acquisition mode of the data (e.g., AXT2 denotes T2 brain MRI scans)
  - max (float): dynamic range of the data
  - norm (float): norm of the kspace
  - patient_id (str): the patient's id whose measurements were recorded
docstr: Extract data array and metadata from the loaded data and return them.
  This function returns two objects, first is numpy array of image data, second is dict of metadata.
  
  Args:
      dat: a dictionary loaded from an h5 file
docstr_tok: ["Extract","data","array","and","metadata","from","the","loaded","data","and","return","them",".","This","function","returns","two","objects",",","first","is","numpy","array","of","image","data",",","second","is","dict","of","metadata",".","Args",":","dat",":","a","dictionary","loaded","from","an","h5","file"]
code: def get_data(self, dat: dict) -> tuple[ndarray, dict]:
      """
      Extract data array and metadata from the loaded data and return them.
      This function returns two objects, first is numpy array of image data, second is dict of metadata.
  
      Args:
          dat: a dictionary loaded from an h5 file
      """
      header = self._get_meta_dict(dat)
      data: ndarray = np.array(dat[FastMRIKeys.KSPACE])
      header[FastMRIKeys.MASK] = (
          np.expand_dims(np.array(dat[FastMRIKeys.MASK]), 0)[
              None, ..., None
          ]
          if FastMRIKeys.MASK in dat.keys()
          else np.zeros(data.shape)
      )
      return data, header
  
file_path: MONAI/monai/apps/reconstruction/fastmri_reader.py
imports: from __future__ import annotations
  import os
  from collections.abc import Sequence
  import numpy
  from numpy import ndarray
  from monai.config import PathLike
  from monai.data.image_reader import ImageReader
  from monai.data.utils import is_supported_format
  from monai.utils import FastMRIKeys, optional_import, require_pkg
label_desc: Use image node_id 3 for calling the FastMRIReader obj's underlying member method code with example usage: obj.get_data(dat) and returns: data,  header