Exists: def of Base
Import: import Base
Lines 145-146 of Base/base.bend: https://jend.leeeet.dev/read.txt?path=Base/base.bend&start_line=145&end_line=146

import Base

def Exists(-A: Type, -B: @-x: A -> Type) -> Type:
  Sigma<&1, &1, A, B>

Uses (1):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Sigma