old_contents: import React from 'react';
  import Entity from '../entity/entity-component';
  import styles from './board-style';
  
  export default ({board, entities, toggleValue}) => (
    <div style={styles.comp}>
      {
        board.map((row, x) => {
          return (
            <div key={x} style={styles.row}>
              {
                row.map((column, y) => {
                  const id = `${x}|${y}`;
                  return (
                    <div key={id} style={styles.column}>
                      <Entity
                        id={id}
                        value={entities.details[id].value}
                        toggleValue={toggleValue}
                        colour={entities.details[id].colour}
                        />
                    </div>
                  );
                })
              }
            </div>
          );
        })
      }
    </div>
  );
  
new_contents: import React from 'react';
  import Entity from '../entity/entity-component';
  import styles from './board-style';
  
  export default ({board, entities, toggleValue}) => (
    <div style={styles.comp}>
      {
        board.map((row, y) => {
          return (
            <div key={y} style={styles.row}>
              {
                row.map((column, x) => {
                  const id = `${x}|${y}`;
                  return (
                    <div key={id} style={styles.column}>
                      <Entity
                        id={id}
                        value={entities.details[id].value}
                        toggleValue={toggleValue}
                        colour={entities.details[id].colour}
                        />
                    </div>
                  );
                })
              }
            </div>
          );
        })
      }
    </div>
  );
  
subject: Fix variable names