abstract type AbstractTask end

abstract type AbstractComputeTask  <: AbstractTask end
abstract type AbstractDataTask     <: AbstractTask end

struct DataTask <: AbstractDataTask
   data::UInt64
end

# S task with 1 child
struct ComputeTaskS1 <: AbstractComputeTask
end

# S task with 2 children
struct ComputeTaskS2 <: AbstractComputeTask
end

# P task with 0 children
struct ComputeTaskP <: AbstractComputeTask
end

# v task with 2 children
struct ComputeTaskV <: AbstractComputeTask
end

# u task with 1 child
struct ComputeTaskU <: AbstractComputeTask
end

# task that sums all its inputs, n children
struct ComputeTaskSum <: AbstractComputeTask
end

struct FusedComputeTask{T1<:AbstractComputeTask, T2<:AbstractComputeTask} <: AbstractComputeTask
end

get_types(::FusedComputeTask{T1, T2}) where {T1, T2} = (T1, T2)