Random examples...

So try to guess what the following things do...

Off[General::spell1];

g = 
        Table[
If[BitAnd[x, y] == 0, 
            Rectangle[{x, y}, 1 + {x, y}], {}], 
{x, 0, 
            63}, {y, 0, 63}];
g = Flatten[g];
Show[Graphics[g]];

f[n_] := 
        Module[{t}, 
t = 
            1; 
Do[
t = 
              t*i, 
{i, 2, n}]; 
Return[
            t];
];
f[5]

h[n_] := 
        Module[{a, b, c}, 
a = 0; 
b = 
            1; 
Do[
c = 
              a + b; 
a = b; 
b = 
              c, 
{i, 2, n}]; 
Return[
            b];
];
\(\(Do[
Print[i, "  ", 
          h[i]], 
{i, 1, 
          10}
];\)


\)

h[n_] := 
        Module[{a, b, c}, 
a = 0; 
b = 
            1; 
Do[
c = 
              a + b; 
a = b; 
b = 
              c; 
{i, 2, n}]; 
Return[
            b];
];
Table[{i, h[i]}, {i, 1, 10}] // MatrixForm

x = 1;
leftOrRight := 
        Module[{}, 
x = 
            x + (-1)^Random[Integer]; 
Return[
            x];
];
walk = Table[leftOrRight, {200}];
ListPlot[walk,  
        PlotJoined -> 
          True];

flips[n_] := 
        Module[{heads}, 
heads = 
            0; 
Do[
If[ 
              Random[Integer] == 
                1,  heads++], 
{n}]; 
Return[
            heads];
];
nFlips  =  25;
experiment = 
        Table[flips[nFlips], {100 nFlips}];
count[h_, exp_] := 
        Length[Position[exp, h]];
<< Graphics`;
BarChart[ 
        Table[ count[i, experiment],  {i, 0, 
            nFlips}]];

g = 
        Table[
If[BitAnd[x, y, z] == 0, 
            Cuboid[{x, y, z}], {}], 
{x, 0, 15}, {y, 0, 
            15}, {z, 0, 15}];

    g = Flatten[g];

    Show[Graphics3D[g]];