docs: def build_extension(self, ext):
          """
          build clrmagic.dll using csc or mcs
          """
          if sys.platform == "win32":
              _clr_compiler = "C:\\Windows\\Microsoft.NET\\Framework\\v4.0.30319\\csc.exe"
          else:
              _clr_compiler = "mcs"
          cmd = [ 
              _clr_compiler,
              "/target:library",
              "clrmagic.cs"
          ]
          check_call(" ".join(cmd), shell=True)