Ensure an argument is wrapped in an array

ensure_array.rb

# Approach alpha is good if you know for certain that you're dealing with
# 1-dimensional arrays.
#
def alpha(parm)
  parm = [parm].flatten
end

# Approach beta works if you need to support multi-dimensional arrays because it
# doesn't rely on #flatten.
#
def beta(parm)
  parm = [parm] unless parm.is_a? Array
end