def get_min_max_value(dfg):
    """
    Gets min and max value assigned to edges
    in DFG graph

    Parameters
    -----------
    dfg
        Directly follows graph

    Returns
    -----------
    min_value
        Minimum value in directly follows graph
    max_value
        Maximum value in directly follows graph
    """
    min_value = 9999999999
    max_value = -1

    for edge in dfg:
        if dfg[edge] < min_value:
            min_value = dfg[edge]
        if dfg[edge] > max_value:
            max_value = dfg[edge]

    return min_value, max_value