title: Adding a new column in dataframe conditionally
body: <p>I have a dataframe as follows:</p>
  <pre><code>| Time  | A     | B     |C    |
  | ----  |--     | ----  |---- |
  | 1.0   |    0  |   1   |  0  |
  | 2.0   |    1  |   1   |  0  |
  | 3.0   |    1  |   1   |  1  |
  | 4.0   |    0  |   1   |  1  |
  | .     |    .  |   .   |  .  |
  | 1000.0|    1  |   1   |  1  |
  </code></pre>
  <p>I want to write to a new column D=1 whenever A==1 &amp; B==1 &amp; C==1 and 0 otherwise</p>