update readme (#19)

README.md

@@ -26,7 +26,7 @@ execution, "what was the path of asynchronous functions that got me here"?
 ## Terminology
 One of the key challenges with "asynchronous context" is the lack of agreed upon terminology and semantics.  Let's define some:
 
-1.  `Execution Frame` - An `Execution Frame` is a period of program execution, defined precisely as the period of time that a special function, called a `Continuation`, is executing. At a lower level of abstraction, you can think of an `Execution Frame` as the period of time from when specific call frame is pushed on the stack, until that call frame is unwound off of the stack. Not all functions are `Continuations` (more on that below).   
+1.  `Execution Frame` - An `Execution Frame` is a period of program execution, defined precisely as the period of time that a special function, called a `Continuation`, is executing. At a lower level of abstraction, you can think of an `Execution Frame` as the period of time from when specific call frame is pushed on the stack, until that call frame is unwound off of the stack. Not all functions are `Continuations` (more on that below).  A specific instance of a `Continuation` can be invoked multiple times; each invocation corresponds to a unique `Execution Frame`.
 
 2.  `Continuation` - A `Continuation` is a JavaScript function created in one `Execution Frame` and passed to a host library to be invoked later.  Upon invocation, a `Continuation` creates a new unique `Execution Frame`.  For example, when we call `setTimeout(function c() {}, 1000)`, `setTimeout` is invoked in one `Execution Frame`, with the caller passing a `Continution` (namely `c`) as a parameter.  When `c` is invoked after the timeout period, a new `Execution Frame` is created, and when `c` completes, that `Execution Frame` is completed.