Length (entry count) of an axis.
Examples
# Mirrors readers.jl jldoctest at line 487.
axis_length(example_metacells_daf(), "type") # 4
#> [1] 4
Length (entry count) of an axis.
# Mirrors readers.jl jldoctest at line 487.
axis_length(example_metacells_daf(), "type") # 4
#> [1] 4