code: def l2_afa_schema(settings=None):
      """Define schema for LI L2 AFA product."""
      settings = settings or {}
      npix = settings.get("num_pixels", 120)
      nacc = settings.get("num_accumulations", 20)
  
      return {
          "providers": settings.get("providers", {}),
          "variable_path": settings.get("variable_path", ""),
          "dimensions": accumulation_dimensions(nacc, npix),
          "variables": {
              "accumulation_start_times": {
                  "format": "f4",
                  "shape": ("accumulations",),
                  "long_name": "Accumulation start time",
                  "units": "seconds since 2000-01-01 00:00:00.0",
                  "default_data": lambda: np.linspace(0.0, 1.0, nacc),
              },
              "accumulated_flash_area": {
                  "format": "u4",
                  "shape": ("pixels",),
                  "fill_value": 4294967295,
                  "long_name": "Number of contributing unique flashes to each pixel",
                  "default_data": lambda: np.mod(np.arange(npix), 10)
                  + 1,
              },
              "mtg_geos_projection": mtg_geos_projection(),
              "x": fci_grid_definition("X", npix),
              "y": fci_grid_definition("Y", npix),
          },
      }
  
imports: from datetime import datetime
  import numpy
  import xarray
  from satpy.tests.reader_tests.test_netcdf_utils import FakeNetCDF4FileHandler
label_desc: Use image node_id 6 for calling a global function with example usage: l2_afa_schema(settings) and returns: dict