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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 get_selections(pattern=None, state=None):
    '''
    View package state from the dpkg database.

    Returns a dict of dicts containing the state, and package names:

    .. code-block:: python

        {'<host>':
            {'<state>': ['pkg1',
                         ...
                        ]
            },
            ...
        }

    CLI Example:

    .. code-block:: bash

        salt '*' pkg.get_selections
        salt '*' pkg.get_selections 'python-*'
        salt '*' pkg.get_selections state=hold
        salt '*' pkg.get_selections 'openssh*' state=hold
    '''
    ret = {}
    cmd = ['dpkg', '--get-selections']
    cmd.append(pattern if pattern else '*')
    stdout = __salt__['cmd.run_stdout'](cmd,
                                        output_loglevel='trace',
                                        python_shell=False)
    ret = _parse_selections(stdout)
    if state:
        return {state: ret.get(state, [])}
    return ret