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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 d_deta_from_phalf(arr, pfull_coord):
 """Compute pressure level thickness from half level pressures."""

    d_deta = arr.diff(dim=internal_names.PHALF_STR, n=1)
    return replace_coord(d_deta, internal_names.PHALF_STR,
                         internal_names.PFULL_STR, pfull_coord)