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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def GetHasherNamesFromString(cls, hasher_names_string):
 """Retrieves a list of a hasher names from a comma separated string. Takes a string of comma separated hasher names transforms it to a list of hasher names. Args: hasher_names_string (str):
 comma separated names of hashers to enable, the string 'all' to enable all hashers or 'none' to disable all hashers. Returns: list[str]: names of valid hashers from the string, or an empty list if no valid names are found. """

    hasher_names = []

    if not hasher_names_string or hasher_names_string.strip() == 'none':
      return hasher_names

    if hasher_names_string.strip() == 'all':
      return cls.GetHasherNames()

    for hasher_name in hasher_names_string.split(','):
      hasher_name = hasher_name.strip()
      if not hasher_name:
        continue

      hasher_name = hasher_name.lower()
      if hasher_name in cls._hasher_classes:
        hasher_names.append(hasher_name)

    return hasher_names