code: def floor(x):
      """Evaluates the floor of an interval"""
      np = import_module("numpy")
      if isinstance(x, (int, float)):
          return interval(np.floor(x))
      elif isinstance(x, interval):
          if x.is_valid is False:
              return interval(-np.inf, np.inf, is_valid=False)
          else:
              start = np.floor(x.start)
              end = np.floor(x.end)
              # continuous over the argument
              if start == end:
                  return interval(start, end, is_valid=x.is_valid)
              else:
                  # not continuous over the interval
                  return interval(start, end, is_valid=None)
      else:
          return NotImplementedError
  
imports: from functools import reduce
  from sympy.plotting.intervalmath import interval
  from sympy.external import import_module
label_desc: Use image node_id 18 for calling a global function with example usage: floor(x) and returns: interval, NotImplementedError, interval, interval, interval