def rep_hill(x, n):
    """Dimensionless production rate for a gene repressed by x.

    Parameters
    ----------
    x : float or NumPy array
        Concentration of repressor.
    n : float
        Hill coefficient.

    Returns
    -------
    output : NumPy array or float
        1 / (1 + x**n)
    """
    return 1.0 / (1.0 + x ** n)