def METHOD_NAME(self, geo_model):
    mesh_header_size = 128
    file_header_size = 86
    ver, tri = geo_model.solutions.vertices[0], geo_model.solutions.edges[0]
    ver_ravel, tri_ravel, n_vtx_coord, n_triangles = gtr.mesh_preprocess(ver, tri)
    data_block_size_no_header = (n_vtx_coord + n_triangles) * 4 + mesh_header_size
    # Write header
    header_bytes = gtr.write_file_header_block(n_data_blocks=1,
                                               size_data_blocks=data_block_size_no_header + gtr.rexDataBlockHeaderSize,
                                               start_data=file_header_size)
    # Write data block
    data_bytes = gtr.write_data_block_header(size_data=data_block_size_no_header,
                                             data_id=1, data_type=3, version_data=1)
    # Write mesh block
    mesh_header_bytes = gtr.write_mesh_header(n_vtx_coord / 3, n_triangles / 3,
                                              start_vtx_coord=gtr.mesh_header_size,
                                              start_nor_coord=gtr.mesh_header_size + n_vtx_coord * 4,
                                              start_tex_coord=gtr.mesh_header_size + n_vtx_coord * 4,
                                              start_vtx_colors=gtr.mesh_header_size + n_vtx_coord * 4,
                                              start_triangles=gtr.mesh_header_size + n_vtx_coord * 4,
                                              name='test_a')
    mesh_block_bytes = gtr.write_mesh_coordinates(ver_ravel, tri_ravel)
    all_bytes = header_bytes + data_bytes + mesh_header_bytes + mesh_block_bytes
    if False:
        gtr.write_file(all_bytes, 'DEP/rexfiles/one_mesh_test')