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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 commit_author(sha1=''):
 # type: (str) -> Author """ Return the author of the given commit. Args: sha1 (str):
 The sha1 of the commit to query. If not given, it will return the sha1 for the current commit. Returns: Author: A named tuple ``(name, email)`` with the commit author details. """

    with conf.within_proj_dir():
        cmd = 'git show -s --format="%an||%ae" {}'.format(sha1)
        result = shell.run(
            cmd,
            capture=True,
            never_pretend=True
        ).stdout
        name, email = result.split('||')
        return Author(name, email)