def is_values(*indexes) # rubocop:disable Style/PredicateName
      bool_array = @keys.map { |r| indexes.include?(r) }
      Daru::Vector.new(bool_array)
    end
@note Do not use it to check for Float::NAN as
Float::NAN == Float::NAN is false
Return vector of booleans with value at ith position is either
true or false depending upon whether index value at position i is equal to
any of the values passed in the argument or not
@param indexes [Array] values to equate with
@return [Daru::Vector] vector of boolean values
@example
dv = Daru::Index.new [1, 2, 3, :one, 'one']
dv.is_values 1, 'one'
# => #<Daru::Vector(5)>
#     0  true
#     1  false
#     2  false
#     3  false
#     4  true