code: def atan(x):
      """evaluates the tan inverse of an interval"""
      np = import_module("numpy")
      if isinstance(x, (int, float)):
          return interval(np.arctan(x))
      elif isinstance(x, interval):
          start = np.arctan(x.start)
          end = np.arctan(x.end)
          return interval(start, end, is_valid=x.is_valid)
      else:
          raise NotImplementedError
  
imports: from functools import reduce
  from sympy.plotting.intervalmath import interval
  from sympy.external import import_module
label_desc: Use image node_id 5 for calling a global function with example usage: atan(x) and returns: interval, interval