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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 lookup(alias):
 """ Tries to find a matcher callable associated to the given alias. If an exact match does not exists it will try normalizing it and even removing underscores to find one. """


    if alias in matchers:
        return matchers[alias]
    else:
        norm = normalize(alias)
        if norm in normalized:
            alias = normalized[norm]
            return matchers[alias]

    # Check without snake case
    if -1 != alias.find('_'):
        norm = normalize(alias).replace('_', '')
        return lookup(norm)

    return None