Let 
 be analytic and bounded on a punctured open disk 
, then 
 exists, and the function defined by 
| 
 
(1)
 
 | 
is analytic.
Let 
 be analytic and bounded on a punctured open disk 
, then 
 exists, and the function defined by 
| 
 
(1)
 
 | 
is analytic.
Weisstein, Eric W. "Riemann Removable Singularity Theorem." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/RiemannRemovableSingularityTheorem.html