In the Environment Variables section the examples use the " (double quote) character to delimit a variable name that has reserved characters where fhirpath itself defines ` (backtic)

%"vs-[name]" // (string) full url for the provided HL7 value set with id [name]
%"ext-[name]" // (string) full url for the provided HL7 extension with id [name] 

should be

%`vs-[name]` // (string) full url for the provided HL7 value set with id [name]
%`ext-[name]` // (string) full url for the provided HL7 extension with id [name]

and 
Observation.component.where(code.memberOf(%`vs-observation-vitalsignresult`))
and
%`us-zip` = '[0-9]{5}(-[0-9]{4}){0,1}'
 
Also, in the factory section the example for creating a Coding shows calling the Quantity function
 
Creates a Coding: <code>%factory.Quantity('http://loinc.org', '1234-5, 'An example test', '1.02')</code>
That should read Coding