text: import inflect
  
  p = inflect.engine()
  
  
  def test_compound_1():
      assert p.singular_noun("hello-out-there") == "hello-out-there"
  
  
  def test_compound_2():
      assert p.singular_noun("hello out there") == "hello out there"
  
  
  def test_compound_3():
      assert p.singular_noun("continue-to-operate") == "continue-to-operate"
  
  
  def test_compound_4():
      assert p.singular_noun("case of diapers") == "case of diapers"
  
  
  def test_unit_handling_degree():
      test_cases = {
          "degree celsius": "degrees celsius",
          # 'degree Celsius': 'degrees Celsius',
          "degree fahrenheit": "degrees fahrenheit",
          "degree rankine": "degrees rankine",
          "degree fahrenheit second": "degree fahrenheit seconds",
      }
      for singular, plural in test_cases.items():
          assert p.plural(singular) == plural
  
  
  def test_unit_handling_fractional():
      test_cases = {
          "pound per square inch": "pounds per square inch",
          "metre per second": "metres per second",
          "kilometre per hour": "kilometres per hour",
          "cubic metre per second": "cubic metres per second",
          "dollar a year": "dollars a year",
          # Correct pluralization of denominator
          "foot per square second": "feet per square second",
          "mother-in-law per lifetime": "mothers-in-law per lifetime",
          "pound-force per square inch": "pounds-force per square inch",
      }
      for singular, plural in test_cases.items():
          assert p.plural(singular) == plural
  
  
  def test_unit_handling_combined():
      test_cases = {
          # Heat transfer coefficient unit
          "watt per square meter degree celsius": "watts per square meter degree celsius",
          "degree celsius per hour": "degrees celsius per hour",
          "degree fahrenheit hour square foot per btuit inch": (
              "degree fahrenheit hour square feet per btuit inch"
          ),
          # 'degree Celsius per hour': 'degrees Celsius per hour',
          # 'degree Fahrenheit hour square foot per BtuIT inch':
          #   'degree Fahrenheit hour square feet per BtuIT inch'
      }
      for singular, plural in test_cases.items():
          assert p.plural(singular) == plural
  