input: Write a python function to categorize a number based on given criteria.
  assert define_category(10, {"low": [0, 15], "medium": [16, 30], "high": [31, 99]}) == "low"
  assert define_category(20, {"low": [0, 15], "medium": [16, 30], "high": [31, 99]}) == "medium"
  assert define_category(50, {"low": [0, 15], "medium": [16, 30], "high": [31, 99]}) == "high"
  assert define_category(101, {"low": [0, 15], "medium": [16, 30], "high": [31, 99]}) == "not found"
output: def define_category(number, categories):
      for category, range_ in categories.items():
          if range_[0] <= number <= range_[1]:
              return category
      return "not found"