docs: def check_module_installed(modname):
      """
      Check if a python module is installed without attempting to import it.
      Note, that if ``modname`` indicates a child module, the parent module is
      always loaded.
  
      Args:
          modname (str):  module name
  
      Returns:
          bool: found
  
      References:
          http://stackoverflow.com/questions/14050281/module-exists-without-importing
  
      CommandLine:
          python -m utool.util_import check_module_installed --show --verbimp --modname=this
          python -m utool.util_import check_module_installed --show --verbimp --modname=guitool
          python -m utool.util_import check_module_installed --show --verbimp --modname=guitool.__PYQT__
          python -m utool.util_import check_module_installed --show --verbimp --modname=ibeis.scripts.iccv
  
      Example:
          >>> # ENABLE_DOCTEST
          >>> from utool.util_import import *  # NOQA
          >>> import utool as ut
          >>> modname = ut.get_argval('--modname', default='this')
          >>> is_installed = check_module_installed(modname)
          >>> is_imported = modname in sys.modules
          >>> print('module(%r).is_installed = %r' % (modname, is_installed))
          >>> print('module(%r).is_imported = %r' % (modname, is_imported))
          >>> assert 'this' not in sys.modules, 'module(this) should not have ever been imported'
      """
      import pkgutil
      if '.' in modname:
          # Prevent explicit import if possible
          parts = modname.split('.')
          base = parts[0]
          submods = parts[1:]
          loader = pkgutil.find_loader(base)
          if loader is not None:
              # TODO: check to see if path to the submod exists
              submods
              return True
      loader = pkgutil.find_loader(modname)
      is_installed = loader is not None
      return is_installed