def _get_bounds(z, b, wl, x0, xRes):
    """
    Gets the indices of range of wavelength that the wavelength wl is in
    with the size of some initial wavelength range.

    Used for checking if species with multiple lines (as in the OVI doublet)
    fit all lines appropriately.

    **Parameters**

    :z: float

        redshift

    :b: (3) ndarray/list

        initial bounds in form [i0,i1,i2] where i0 is the index of the
        minimum flux for the complex, i1 is index of the lower wavelength
        edge of the complex, and i2 is the index of the higher wavelength
        edge of the complex.

    :wl: float

        unredshifted wavelength of the peak of the new region

    :x0: float

        wavelength of the index 0

    :xRes: float

        difference in wavelength for two consecutive indices

    **Returns**

    :indices: (2) tuple

        Tuple (i1,i2) where i1 is the index of the lower wavelength bound of
        the new region and i2 is the index of the higher wavelength bound of
        the new region
    """
    r = [-b[1] + 100 + b[0], b[2] + 100 - b[0]]
    redWl = (z + 1) * wl
    iRedWl = int((redWl - x0) / xRes)
    indices = iRedWl - r[0], iRedWl + r[1]
    return indices
