The operators [, [[, and $ propagate the class
correctly.
## S3 method for class 'phylo':
print(x, printlen = 6 ,...)
## S3 method for class 'multiPhylo':
print(x, details = FALSE ,...)
## S3 method for class 'multiPhylo':
[(x, i)
## S3 method for class 'multiPhylo':
[[(x, i)
## S3 method for class 'multiPhylo':
$(x, name)
## S3 method for class 'multiPhylo':
str(object, ...)"phylo" or "multiPhylo"."multiPhylo"."phylo" ([[, $) or of class
"multiPhylo" ([[), or NULL.read.tree, summary.phylo,
print for the generic R function