* representation to this hash code.
   *
   * <p><b>Security note:</b> this method uses a constant-time (not short-circuiting) implementation
   * to protect against <a href="http://en.wikipedia.org/wiki/Timing_attack">timing attacks</a>.
   */
  @Override
  public final boolean equals(@Nullable Object object) {
    if (object instanceof HashCode) {
      HashCode that = (HashCode) object;

```

</div>

////

當學習[虛擬環境](virtual-environments.md)時，這些資訊將會很有用。

## 結論 { #conclusion }

透過這個教學，你應該對**環境變數**是什麼以及如何在 Python 中使用它們有了基本的了解。

你也可以在 [環境變數的維基百科條目](https://en.wikipedia.org/wiki/Environment_variable) 中閱讀更多。

在許多情況下，環境變數的用途和適用性可能不會立刻顯現。但是在開發過程中，它們會在許多不同的場景中出現，因此瞭解它們是非常必要的。

   * serializable.
   *
   * @param g the second function to apply
   * @param f the first function to apply
   * @return the composition of {@code f} and {@code g}
   * @see <a href="//en.wikipedia.org/wiki/Function_composition">function composition</a>
   */
  public static <A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>

   * serializable.
   *
   * @param g the second function to apply
   * @param f the first function to apply
   * @return the composition of {@code f} and {@code g}
   * @see <a href="//en.wikipedia.org/wiki/Function_composition">function composition</a>
   */
  public static <A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>

    }
    if (result.equals("/..")) {
      result = "/";
    } else if (result.isEmpty()) {
      result = ".";
    }

    return result;
  }

  /**
   * Returns the <a href="http://en.wikipedia.org/wiki/Filename_extension">file extension</a> for
   * the given file name, or the empty string if the file has no extension. The result does not
   * include the '{@code .}'.
   *

import com.google.errorprone.annotations.DoNotMock;
import java.util.Collection;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * An interface for <a
 * href="https://en.wikipedia.org/wiki/Graph_(discrete_mathematics)">graph</a>-structured data,
 * whose edges are anonymous entities with no identity or information of their own.
 *

    }
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two arrays of unsigned {@code int} values <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(int, int)}), the first pair of values that follow any common

 *       approaches to this</a> that should be considered first)
 * </ul>
 *
 * <p>A common alternative to using this class is to find or create a suitable <a
 * href="http://en.wikipedia.org/wiki/Null_Object_pattern">null object</a> for the type in question.
 *
 * <p>This class is not intended as a direct analogue of any existing "option" or "maybe" construct

      if (!Files.isDirectory(parent)) {
        throw new IOException("Unable to create parent directories of " + path);
      }
    }
  }

  /**
   * Returns the <a href="http://en.wikipedia.org/wiki/Filename_extension">file extension</a> for
   * the file at the given path, or the empty string if the file has no extension. The result does
   * not include the '{@code .}'.
   *

 *       approaches to this</a> that should be considered first)
 * </ul>
 *
 * <p>A common alternative to using this class is to find or create a suitable <a
 * href="http://en.wikipedia.org/wiki/Null_Object_pattern">null object</a> for the type in question.
 *
 * <p>This class is not intended as a direct analogue of any existing "option" or "maybe" construct