code: def _fetch_map_string(self, m):
      out = m._parent.render()
      out_str = "".join(out.split())
      return out_str
  
imports: import geopandas
  import numpy
  import pandas
  import pytest
  import shapely
  from packaging.version import Version
  from matplotlib import cm
  from matplotlib import colors
  from branca.colormap import StepColormap
label_desc: Use image node_id 1 for calling the TestExplore obj's underlying member method code with example usage: obj._fetch_map_string(m) and returns: out_str