# sanity check
2‿3⥊↕4 # >⟨0‿1‿2,3‿0‿1⟩
5⥊3 # 3‿3‿3‿3‿3
3⥊↕10 # 0‿1‿2
5⥊1‿2 # 1‿2‿1‿2‿1
⟨⟩⥊1‿2‿3 # <1

# general
∘‿0⥊↕10 # err
⌊‿0⥊↕10 # err
↑‿0⥊↕10 # err
⌽‿0⥊↕10 # err
⟨∘⟩⥊2‿3‿4⥊↕24 # ↕24
⟨⌊⟩⥊2‿3‿4⥊↕24 # ↕24
⟨↑⟩⥊2‿3‿4⥊↕24 # ↕24
⟨⌽⟩⥊2‿3‿4⥊↕24 # ↕24
2‿∘‿4⥊↕24 # 2‿3‿4⥊↕24
2‿⌊‿4⥊↕24 # 2‿3‿4⥊↕24
2‿↑‿4⥊↕24 # 2‿3‿4⥊↕24
2‿⌽‿4⥊↕24 # 2‿3‿4⥊↕24
⟨∘⟩⥊⟨⟩ # ⟨⟩
⟨⌊⟩⥊⟨⟩ # ⟨⟩
⟨↑⟩⥊⟨⟩ # ⟨⟩
⟨⌽⟩⥊⟨⟩ # ⟨⟩

# ∘
∘‿2⥊↕10 # 5‿2⥊↕10
2‿∘⥊↕10 # 2‿5⥊↕10
∘‿2⥊↕9 # err
∘‿1⥊3 # 1‿1⥊3
∘‿2⥊3 # err
∘‿3⥊⟨⟩ # 0‿3⥊⟨⟩

# ↑
↑‿3⥊↕4 # 2‿3⥊0‿1‿2‿3‿0‿0
↑‿3⥊⟨⟩ # 0‿3⥊⟨⟩
↑‿3⥊4 # 1‿3⥊4‿0‿0
↑‿3⥊<¨↕10 # 4‿3⥊12↑<¨↕10 # whatever that is..

# ⌊
⌊‿4⥊↕10 # 2‿4⥊↕10
⌊‿5⥊↕10 # 2‿5⥊↕10
⌊‿5⥊↕3  # 0‿5⥊0
⌊‿5⥊0   # 0‿5⥊0

# ⌽
⌽‿3⥊↕10 # 4‿3⥊↕10
3‿⌽⥊↕10 # 3‿4⥊↕10
10‿⌽⥊↕3 # 10‿1⥊↕3