parameters: (env, version_var1, version_var2, flags_var)
return_statement: return None
docstring: if $version_var1 or $version_var2 is not empty, returns env[flags_var], otherwise returns None
      :param env:
      :param version_var1:
      :param version_var2:
      :param flags_var:
      :return:
docstring_summary: if $version_var1 or $version_var2 is not empty, returns env[flags_var], otherwise returns None
      :param env:
      :param version_var1:
      :param version_var2:
      :param flags_var:
      :return:
docstring_tokens: if $version_var1 or $version_var2 is not empty returns env [ flags_var ] otherwise returns None : param env : : param version_var1 : : param version_var2 : : param flags_var : : return :
function: def __lib_either_version_flag(env, version_var1, version_var2, flags_var):
      """
      if $version_var1 or $version_var2 is not empty, returns env[flags_var], otherwise returns None
      :param env:
      :param version_var1:
      :param version_var2:
      :param flags_var:
      :return:
      """
      try:
          if env.subst('$' + version_var1) or env.subst('$' + version_var2):
              return env[flags_var]
      except KeyError:
          pass
      return None
function_tokens: def __lib_either_version_flag ( env , version_var1 , version_var2 , flags_var ) : try : if env . subst ( '$' + version_var1 ) or env . subst ( '$' + version_var2 ) : return env [ flags_var ] except KeyError : pass return None