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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 mod_init(low):
    '''
    Set a flag to tell the install functions to refresh the package database.
    This ensures that the package database is refreshed only once during
    a state run significantly improving the speed of package management
    during a state run.

    It sets a flag for a number of reasons, primarily due to timeline logic.
    When originally setting up the mod_init for pkg a number of corner cases
    arose with different package managers and how they refresh package data.

    It also runs the "ex_mod_init" from the package manager module that is
    currently loaded. The "ex_mod_init" is expected to work as a normal
    "mod_init" function.

    .. seealso::
       :py:func:`salt.modules.ebuild.ex_mod_init`

    '''
    ret = True
    if 'pkg.ex_mod_init' in __salt__:
        ret = __salt__['pkg.ex_mod_init'](low)

    if low['fun'] == 'installed' or low['fun'] == 'latest':
        salt.utils.pkg.write_rtag(__opts__)
        return ret
    return False