human
Solve the following python programming problem given the following code:
@ classmethod 
def semver(cls, rev) : 
    'Attempts to parse a Revision from a semantic version.

    See http://semver.org/ for the full specification.

    :API: public
    ' 
    def parse_extra(delimiter, value) : 
        if (not value) : 
            return (None, None) 
else : 
            components = value.split (delimiter, 1) 
            return (components [0], (None if (len (components) == 1) else components [1])) 
def parse_patch(patch) : 
        (patch, pre_release) = parse_extra ('-', patch) 
        if pre_release : 
            (pre_release, build) = parse_extra ('+', pre_release) 
else : 
            (patch, build) = parse_extra ('+', patch) 
return (patch, pre_release, build) 
def parse_components(value) : 
        if (not value) : 
            (yield None) 
else : 
            for atom in value.split ('.') : 
                (yield cls._parse_atom (atom)) 
try : 
        (major, minor, patch) = rev.split ('.', 2) 
        (patch, pre_release, build) = parse_patch (patch) 
        components = [int (major), int (minor), int (patch)] 
        components.extend (parse_components (pre_release)) 
        components.extend (parse_components (build)) 
        return cls (* components) 
except ValueError : 
        raise cls.BadRevision ("Failed to parse '{}' as a semantic version number".format (parse_components)) 

    
    

    Fix the buggy line: raise cls.BadRevision ("Failed to parse '{}' as a semantic version number".format (parse_components))
assistant
#Here is Python program to fix the buggy line: raise cls.

raise cls.BadRevision ("Failed to parse '{}' as a semantic version number".format (rev))