Dissolve yeast in warm water. Beat 3 eggs in a large mixing bowl; add salt, sugar, dissolved yeast, and butter. To this mixture, add 4 cups of the flour (all at once). Stir in the flour and continue to add 3 more cups of flour until the dough is of a soft consistency. Knead the dough on a floured board until the dough is no longer sticky and is springy to the touch. Place the dough in a greased mixing bowl and cover with a towel. Let rise 1.5 hours, or until doubled in bulk. Punch down the dough, knead it a little, and divide it in 6 pieces. Roll each piece with your hands so they become long, skinny ropes. Braid 3 ropes, pinching the ends together. Repeat the process with the other 3 ropes. Place each braided loaf on it`s own greased cookie sheet, cover with a towel, and let rise about an houruntil doubled in bulk. Brush the loaves with the 2 beaten eggs, sprinkle with poppy seeds or sesame seeds (optional). DO NOT PRE-HEAT OVENBake in a 180ºC degree oven about 45 minutes, until the bread is golden-brown.