pub fn avg(zl: ZList(Float)) -> Result(Float, Nil)

pub fn delete_at(zl: ZList(a), i: Int) -> ZList(a)

pub fn freqs_with_size(zl: ZList(a)) -> #(ZList(#(a, Int)), Int)

pub fn group_by(zl: ZList(a), f: fn(a) -> b) -> ZList(
  #(b, ZList(a)),
)

pub fn max_by(zl: ZList(a), f: fn(a) -> Float) -> Result(a, Nil)

pub fn min_by(zl: ZList(a), f: fn(a) -> Float) -> Result(a, Nil)

pub fn replace_at(zl: ZList(a), i: Int, elem: a) -> ZList(a)

pub fn shuffle(zl: ZList(a), seed: Int) -> ZList(a)

pub fn to_list_of_lists(zl: ZList(ZList(a))) -> List(List(a))

pub fn to_zlist_of_zlists(ls: List(List(a))) -> ZList(ZList(a))

pub fn uniq(zl: ZList(a)) -> ZList(a)