from dask import delayed

f = delayed(f)
g = delayed(g)
h = delayed(h)
w = f(g(h(4)))
w.compute()  # lazy computing
w.visualize()

def f(x):
  return sqrt(x + 4)
f = delayed(f)

# Equivalent to definition
@delayed
def f(x):
  return sqrt(x + 4)