Based on the documentation here and all Zabbix releases API documentation.

I have a lookup table like below

PRIORITY_MAP    = {}
PRIORITY_MAP[0] = 'not classified'
PRIORITY_MAP[1] = 'information'
PRIORITY_MAP[2] = 'warning'
PRIORITY_MAP[3] = 'average'
PRIORITY_MAP[4] = 'high'
PRIORITY_MAP[5] = 'disaster'

The problem is the returned trigger "priority" value doesn't match the above table or documentation. For example i have a trigger that is configured as 'HIGH' severity, when triggered it gives me priority = `3`. So it wrongly translates as 'AVERAGE'. When i change the trigger to 'LOW' the priority value returned is '1'.

When i create a trigger i have the following options

Information
Low
Warning
High
Very High
Disaster

Which makes me think my code should be

PRIORITY_MAP    = {}
PRIORITY_MAP[0] = 'Information'
PRIORITY_MAP[1] = 'Low'
PRIORITY_MAP[2] = 'Warning'
PRIORITY_MAP[3] = 'High'
PRIORITY_MAP[4] = 'Very High'
PRIORITY_MAP[5] = 'Disaster'

So the documentation for API "Trigger object" is wrong, should be

Severity of the trigger. 

Possible values are: 
0 - information; 
1 - low; 
2 - warning; 
3 - high; 
4 - very high; 
5 - disaster.