Hi firmai,

Thanks for creating deltapy! I just wanted to point out that not all functions are look ahead safe: their values change if new data is appended to the dataframe, making them hard to use in real life. For example:

a = transform.instantaneous_phases(df, ["close"]).iloc[
    -2
]
b = transform.instantaneous_phases(df.iloc[:-1], ["close"]).iloc[-1]
pd.testing.assert_series_equal(a,b) # -> this fails

I havent tested all, but this applies atleast to the transform.bkb and transform.instantaneous_phases functions.