S3 method for the + operator to combine two `eam_summarise_by_spec`
objects into a single spec that will apply both operations.
Usage
# S3 method for class 'eam_summarise_by_spec'
e1 + e2
Arguments
- e1
First eam_summarise_by_spec or eam_summarise_by_tbl object
- e2
Second eam_summarise_by_spec or eam_summarise_by_tbl object
Value
A combined eam_summarise_by_spec object