Function to validate a dataframe returning a bool - model composition

[mb-915]

Hello,

What I sometimes have, is a base model, and multiple inhited models with groups of optionnal columns like in the following (made-up) example : 

class ObservedAnimal(pa.DataFrameModel):
    name: Series[str]
    specie: Series[str]

class Bird(ObservedAnimal):
    color: Series[str]
    wing_length: Series[str]

class Mammal():
    weight: Series[float]

class Flying(ObservedAnimal):
    flying_height: Series[float]
    speed: Series[float]

I then want to check if the columns are present : what I would like to have instead of a validate function that raises an error, is a validate_bool function that returns a bool:

plot = plot_this(observed_animals)
if Flying.validate_bool(observed_animals) and Mammal.validate_bool(observed_animals):
    plot += batplot(observed_animals)

or maybe even be able to create composed validation models

plot = plot_this(observed_animals)
if (Flying | Mammal).validate_bool(observed_animals):
    plot += batplot(observed_animals)

Do you think it could be useful. Or is there already a way to do something like that without an helper function ?