code: def expanduser(path):
      
      if '~' not in path:
          return path
  
      if os.name == "nt":
          if 'HOME' in os.environ:
              userhome = os.environ['HOME']
          elif 'USERPROFILE' in os.environ:
              userhome = os.environ['USERPROFILE']
          elif 'HOMEPATH' in os.environ:
              drive = os.environ.get('HOMEDRIVE', '')
              userhome = os.path.join(drive, os.environ['HOMEPATH'])
          else:
              return path
      else:
          userhome = os.path.expanduser('~')
  
      def _expanduser(path):
          return EXPANDUSER_RE.sub(
              lambda m: m.groups()[0] + userhome + m.groups()[1],
              path)
  
      # only replace '~' if it's at start of string or is preceeded by pathsep or
      # ';' or whitespace; AND, is followed either by sep, pathsep, ';', ' ' or
      # end-of-string.
      #
      return os.path.normpath(_expanduser(path))
docs: Expand '~' to home directory in the given string.
  
      Note that this function deliberately differs from the builtin
      os.path.expanduser() on Linux systems, which expands strings such as
      '~sclaus' to that user's homedir. This is problematic in rez because the
      string '~packagename' may inadvertently convert to a homedir, if a package
      happens to match a username.