Calculate theanine amount to add to tea, for the desired theanine/caffeine ratio.

thea.py

def theanine_to_add(grams, ratio=1.5, flavor="black"):
    caffeine_mg_per_gram = dict(
        black=25,
        yerba=10,     # https://erowid.org/plants/yerba_mate/yerba_mate_chemistry2.shtml
        pu_erh=12.5,
    )
    theanine_mg_per_gram = dict(
        black=7.5,    # other sources: 2.7, 12.5
        yerba=0,      # https://www.leaf.tv/articles/what-is-theanine-does-yerba-mate-contain-it/
    )
    theobromine_mg_per_gram = dict(
        yerba=3.4,    # https://erowid.org/plants/yerba_mate/yerba_mate_chemistry2.shtml
    )
    caffeine_content = caffeine_mg_per_gram[flavor] * grams
    theanine_content = theanine_mg_per_gram[flavor] * grams
    print(f"{caffeine_content=}  {theanine_content=}")

    target_theanine_content = caffeine_content * ratio
    print(f"{target_theanine_content=}")

    thanine_mg_to_add = target_theanine_content - theanine_content
    theanine_grams_to_add = thanine_mg_to_add / 1000
    print(f"\n{theanine_grams_to_add=}")

    ml_of_water = 2.5 * theanine_grams_to_add
    print(f"\n{ml_of_water=}")