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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def image_read(filename, dimension=None, pixeltype='float', reorient=False):
 """ Read an ANTsImage from file ANTsR function: `antsImageRead` Arguments --------- filename : string Name of the file to read the image from. dimension : int Number of dimensions of the image read. This need not be the same as the dimensions of the image in the file. Allowed values: 2, 3, 4. If not provided, the dimension is obtained from the image file pixeltype : string C++ datatype to be used to represent the pixels read. This datatype need not be the same as the datatype used in the file. Options: unsigned char, unsigned int, float, double reorient : boolean | string if True, the image will be reoriented to RPI if it is 3D if False, nothing will happen if string, this should be the 3-letter orientation to which the input image will reoriented if 3D. if the image is 2D, this argument is ignored Returns ------- ANTsImage """

    if filename.endswith('.npy'):
        filename = os.path.expanduser(filename)
        img_array = np.load(filename)
        if os.path.exists(filename.replace('.npy', '.json')):
            with open(filename.replace('.npy', '.json')) as json_data:
                img_header = json.load(json_data)
            ants_image = from_numpy(img_array,
                                    origin=img_header.get('origin', None),
                                    spacing=img_header.get('spacing', None),
                                    direction=np.asarray(img_header.get('direction',None)),
                                    has_components=img_header.get('components',1)>1)
        else:
            img_header = {}
            ants_image = from_numpy(img_array)

    else:
        filename = os.path.expanduser(filename)
        if not os.path.exists(filename):
            raise ValueError('File %s does not exist!' % filename)

        hinfo = image_header_info(filename)
        ptype = hinfo['pixeltype']
        pclass = hinfo['pixelclass']
        ndim = hinfo['nDimensions']
        ncomp = hinfo['nComponents']
        is_rgb = True if pclass == 'rgb' else False
        if dimension is not None:
            ndim = dimension

        # error handling on pixelclass
        if pclass not in _supported_pclasses:
            raise ValueError('Pixel class %s not supported!' % pclass)

        # error handling on pixeltype
        if ptype in _unsupported_ptypes:
            ptype = _unsupported_ptype_map.get(ptype, 'unsupported')
            if ptype == 'unsupported':
                raise ValueError('Pixeltype %s not supported' % ptype)

        # error handling on dimension
        if (ndim < 2) or (ndim > 4):
            raise ValueError('Found %i-dimensional image - not supported!' % ndim)

        libfn = utils.get_lib_fn(_image_read_dict[pclass][ptype][ndim])
        itk_pointer = libfn(filename)

        ants_image = iio.ANTsImage(pixeltype=ptype, dimension=ndim, components=ncomp,
            pointer=itk_pointer, is_rgb=is_rgb)

        if pixeltype is not None:
            ants_image = ants_image.clone(pixeltype)

    if (reorient != False) and (ants_image.dimension == 3):
        if reorient == True:
            ants_image = ants_image.reorient_image2('RPI')
        elif isinstance(reorient, str):
            ants_image = ants_image.reorient_image2(reorient)

    return ants_image