1 files changed, 57 insertions, 0 deletions
diff --git a/lib/person.rb b/lib/person.rb
new file mode 100644
index 0000000..a40efbe
--- /dev/null
+++ b/lib/person.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+class Person
+  attr_accessor :name, :gender, :spouse
+
+  def initialize(name, gender, spouse = NilPerson.new)
+    @name = name
+    @gender = gender
+    @spouse = spouse
+  end
+
+  def ==(other)
+    other.is_a?(Person) && name == other.name && gender == other.gender && spouse == other.spouse
+  end
+
+  def eql?(other)
+    self == other
+  end
+
+  def hash
+    [name, gender, spouse].hash
+  end
+
+  def to_s
+    "#{name} (#{gender})"
+  end
+end
+
+class NilPerson
+  def name
+    nil
+  end
+
+  def father
+    self
+  end
+
+  def mother
+    self
+  end
+
+  def gender
+    nil
+  end
+
+  def ==(other)
+    other.is_a?(NilPerson)
+  end
+
+  def eql?(other)
+    self == other
+  end
+
+  def to_s
+    ''
+  end
+end